The present invention relates to a range finding camera i.e. an imaging instrument for scanning a certain field of view and acquiring information on the distance of objects from the camera within that field of view. The principle of measurements depends on measuring the round trip period of time of a light signal from a particular source, to an object where it is reflected towards the camera; the period of time it takes from emission to detection, as far as that particular point is concerned, is directly indicative of the distance of that point from the camera. An entire field of view can be resolved in this fashion and each image point i.e. any point that is capable and does in fact reflect light is identified by such a round trip time and if for example a grey scale or a color scheme is signed to round trip periods then such a range image being colored or a grey scan image does not represent reflectivity but distance of objects in the field of view from the camera.
Range values on a matrix basis or the like can be evaluated and electronically processed otherwise. In this case there is an assignment of grey values, grid projection "false", color codes or the like and an image can be displayed on a suitable monitor. The production of a range image in this fashion realizes a so called active principle that means one does not depend on some kind of mere ambiance and on whatever is received from the ambiance, but of course in order to determine distances by timing, it is required that the light that is being reflected, is in fact produced in an accurately timed relation to the receiving of lights. Owing to this principle then the reflectivity of the object that reflects light i.e. the amplitude of the return light or better the relationship of the amplitude of the light that returns to the amplitude of the light that was transmitted gives another information content namely the regular reflectivity image. There may be reasons for using this information in addition.
The state of the art is exemplarily represented by U.S. Pat. Nos. 4,199,253 and 4,708,473 and German patents 38 40 425; 37 32 347.